Integrated circuits have been manufactured for many years. Manufacturing integrated circuits involves integrating various active and passive circuit elements into a piece of semiconductor material, referred to as a die. The die is then mounted into a ceramic or plastic substrate to form a package. In some applications, these packages are directly attached to a printed circuit board by connecting pins, which are arranged along the periphery or area array of the package. An electronic system can be formed by connecting various integrated circuit packages to a printed circuit board.
As advances in semiconductor manufacturing technology have led to substantially increased numbers of transistors on each integrated circuit, it has become possible to correspondingly increase the functionality of each integrated circuit. In turn, increased functionality has resulted in the need to increase the number of input/output (I/O) connections between the integrated circuit and the rest of the electronic system of which the integrated circuit is a part. One adaptation designed to address the increased need for I/O connections has been to simply add additional pins to the package. Unfortunately, adding pins to the package increases the area consumed by the package.
A further adaptation designed to address the increased need for I/O connections without consuming an unacceptably large amount of area was the development of ball grid array (BGA) packages. A typical example of the BGA packages include a plurality of solder bumps formed by a process commonly referred to as controlled collapsed chip connection (C4). In such a package, a large number of I/O connection terminals are disposed in a two dimensional array over a substantial portion of a major surface of the package. In some instances, BGA packages are directly attached to a supporting substrate such as a printed circuit board.
There is an ever-present trend in the electronics industry toward miniaturization, enhancement of functionality, and increased memory capacity of consumer and computing products. This trend continuously pressures the microelectronics industry. One response to the industry trend has been to make multi-die packaging to provide enhanced functionality, increased memory capacity, and miniaturized consumer and computing products. Many vendors in the semiconductor industry offer a multi-chip, System-on-Chip (SoC), or stacked packaging solution. in an attempt to provide enhanced functionality, increased memory capacity, and miniaturized consumer and computing products. One example of the stacked packages is the combination of a flip chip BGA and Plastic Ball Grid Array (PBGA). The flip chip BGA device has an active surface near the input/output balls while the PBGA device has an active surface more distant from the input/output balls.
An issue related to stacked packages including at least two electronic devices is electromagnetic interference (EMI). EMI is any electromagnetic disturbance that interrupts, obstructs or otherwise degrades or limits the effective performance of electronics or electrical equipment. In the instance of a set of stacked electronic devices, one or both of the electronic devices can operate at a frequency that produces EMI in the other of the electronic devices. EMI induced in one of the stacked electronic devices reduces the effective performance of the entire package.